I'm also reminded that for years, Noink tried to convince the faithful that there was no market for full-frame digital cameras. Canon proved them wrong, first with the 1Ds, and then when they brought out a mid-priced full-frame DSLR (the 5D).
The introduction of a full-frame by Nikon is not preemptive. It's a response to Canon having a virtual monopoly on the FF market. The new camera might be a real corker, but this is an ongoing battle, and Canon will come out with something better in response, whether it's actually needed or not.